The corrosion of metal articles is of obvious economic significance in any industrial application and, as a consequence, the inhibition of such corrosion is a matter of prime consideration. It is particularly significant to users of steel and other ferrous alloys. The corrosion of such ferrous metal alloys is largely a matter of rust formation, which in turn involves the overall conversion of the free metal to its oxides.
The theory which best explains such oxidation of ferrous metal articles postulates the essential presence of both water and oxygen. Even minute traces of moisture are sufficient, according to this theory, to induce dissolution of iron therein and the formation of ferrous hydroxide until the water becomes saturatd with ferrous ions. The presence of oxygen causes oxidation of the resulting ferrous hydroxide to ferric hydroxide, which settles out of solution and is ultimately converted to ferric oxide or rust.
The above sequence of reactions can be prevented, or at least in large measure inhibited, by relatively impermeable coatings which have the effect of excluding moisture and/or oxygen from contact with the metal surface. It is important, therefore, that these coatings adhere tightly to the metal surface and resist flaking, crazing, blistering, powdering, and other forms of loss of adhesion. A satisfactory corrosion-proofing coating, therefore, must have the ability to resist weathering, high hummidity, and corrosive atmospheres such as salt-laden mist or fog, air contaminated with industrial waste, etc., so that a uniform protective film is maintained on all or most of the metal surface.
U.S. Pat. Nos. 3,215,715 and 3,276,916 disclose metal-containing phosphate complexes for inhibiting the corrosion of metal. These complexes are prepared by the reaction of (A) a polyvalent metal salt of the acid phosphate esters derived from the reaction of phosphorus pentoxide with a mixture of a monohydric alcohol and from 0.25 to 4.0 equivalents of a polyhydric alcohol, with (B) at least about 0.1 equivalent of an organic epoxide.
U.S. Pat. No. 3,411,923 discloses metal-containing organic phosphate compositions for inhibiting the corrosion of metals which comprise (A) a metal-containing organic phosphate complex prepared by the process which comprises the reaction of (I) a polyvalent metal salt of an acid phosphate ester derived from the reaction of phosphorus pentoxide or phosphoric acid with a mixture of a monohydric alcohol and from about 0.25 to about 4.0 equivalents of a polyhydric alcohol with (II) at least about 0.1 equivalent of an organic epoxide, and (B) a basic alkali or alkaline earth metal salt of a sulfonic or carboxylic acid having at least about 12 aliphatic carbon atoms, said salt having a metal ratio of at least about 1.1.
The foregoing corrosion-inhibiting compositions are oil-based compositions. That is, they are usually diluted with mineral oil or volatile diluents such as benzene, xylene, aromatic petroleum spirits, turpentine, etc. It would be advantageous to replace these oil-based compositions with water-based compositions wherever possible.
Metal working operations, for example, rolling, forging, hot-pressing, blanking, bending, stamping, drawing, cutting, punching, spinning and the like generally employ a lubricant to facilitate the same. Lubricants greatly improve these operations in that they can reduce the power required for the operation, prevent sticking and decrease wear of dies, cutting bits and the like. In addition, they frequently provide rust inhibiting properties to the metal being treated. These lubricants are usualy oil-based and it would be advantageous to replace such oil-based lubricants with water-based lubricants wherever possible.
The use of drilling fluids in well-drilling operations has been known for at least 100 years. See, for example, the discussion in Kirk-Othmer. "Encyclopedia of Chemical Technology", Second Edition, Vol. 7, pages 287 et seq. Aqueous drilling fluids or muds usually contain a thickening agent such as clay and often a density-increasing agent such as barites. The use of other additives in drilling fluids or muds is also known. See, for example, John McDermott, "Drilling Mud and Fluid Additives", Noyes-Data Corporation, New Jersey, 1973.
Among the types of additives used in drilling muds or fluids are lubricants or lubricity agents. Such additives reduce drag on the drill string and bit and thereby reduce the possibilities of twist off, reduce trip time, lessen differential sticking and lower the amount of energy required to turn the rig (that is, the torque requirements). Methods for evaluating such drilling fluid lubricants are also known. See, for example, the article by Stan E. Alford in "World Oil", July, 1976, Gulf Publishing Company.
Other additives which enhance the lubricating properties of drilling fluids or muds have been reported in the patent literature. See, for example, U.S. Pat. Nos. 3,214,374 and 4,064,055. The use of petroleum sulfonates as extreme pressure additives in oil emulsion and aqueous drilling fluids is also known. See the articcle by M. Rosenberg et al in AIME Petroleum Transactions, Vol. 216 (1959), pages 195-202 and U.S. Pat. No. 4,064,056.
U.S. Pat. No. 4,230,586 discloses aqueous well-drilling fluids which comprise (A) at least one non-Newtonian colloidal disperse system comprising:
(1) solid metal-containing colloidal particles at least a portion of which are predispersed in PA1 (2) at least one liquid dispersing medium; and PA1 (3) as an essential component, at least one organic compound which is soluble in said dispersing medium, the molecules of said organic compound being characterized by a hydrophobic portion and at least one polar substituent
and (B) at least one emulsifier.
Despite the foregoing, the search for effective drilling fluids, which aid in achieving more efficient and economical rotary drilling operations, has continued.